Expanding control for self-feeding boiler tube expanders



EXPANDING CONTROL FOR SELF-FEEDING BOILER TUBE EXPANDERS Filed March 2, 1964 F. F. FISHER Nov. 21, 1967 2 Sheefis-Sheet 1 FIGO4I n a i I 7 2 3 G G H m. H 6 M 7 0 1 2 J \S I? |H r |n nl ad M? a r 1w U \V 8 2 W 2 5 INVENTOR. FRANK F. FISHER ATTORNEYS FIGJI.

Nov. 21, 1967 F. F. FISHER 3,353,336

I EXPANDING CONTROL FOR SELF-FEEDING BOILER TUBE EXPANDER 2 Sheets-Sheet 2 //////AZ/ h Filed March 2, 1964 M f O 6 3 5 G INVENTOR.

FRANK F. FISHER ATTORNEYS United States Patent Office 3,353,386 Fatented Nov. 21, 1967 3,353,386 EXPANDING CUNTROL FOR SELF-FEEDING BOILER TUBE EXPANDERS Frank F. Fisher, 1411]. Sussex, Detroit, Mich. 48227 Filed Mar. 2, 1964, Ser. No. 348,355 14 Claims. (c1. 72-32) The invention relates to boiler making and refers more specifically to a method of and means for separately measuring the expanding belling and resistance to forward movement forces exerted on an expander roller and an expanding control for self-feeding boiler tube expanders.

Cold working of tube ends by the tube expanding or tube rolling to form joints for fastening the tubes securely to drums, headers or other objects has been practiced for many years. The quality of the joint formed between the tube and header by expanding or rolling is sensitive to overworking or underworking of the tube end during forming of the joint. Therefore, means must be provided for indicating, during the forming of the joint, when the expanding of the tube end has been suflicient to provide the optimum joint between the tube end and header.

With small tubes, such as found in condensers and feed water heaters, the torque applied to the mandrel of a tube expander has been measured as an indication of the working of the end of the tube being expanded. While such torque measurements have been successful in controlling tube expanders to produce satisfactory joints with the smaller tubes, the torque control technique of tube expanding is of little value in the expanding of boiler tubes since most boiler codes require a flared end to be formed on the boiler tube and the flared end is normally and most efficiently produced simultaneously with the expanding of the end of the boiler tube so that the applied torque is divided between the expanding and flaring of the tube end.

Also, the known torque controlled tube expanders have limited use in expanding boiler tubes since most boiler tube joints are located in drums which are too small in diameter for access and direct expander application or in small headers that must be rolled from the outside. Joints in such locations must, because of their nature, be rolled by means of angle drives, knuckle joints, special gear drives or other power transmitting devices that consume unknown and varying amounts of power.

Some specially designed expanders for boiler tubes and the like have been produced particularly in Europe. However, most of these expanders have controls based on applied torque, are bulky and have a low output per man hour since they control only the degree of expanding and a separate flaring operation is required to finish a joint. Consequently prior specially designed expanders have found little favor in the United States.

It is therefore one of the objects of the present invention to provide an improved expanding control for boiler tube expanders.

Another object is to provide an expanding control for a self-feeding boiler tube expander including means operably associated with at least one of the rollers of the tube expander for providing an indication of the rolling in of a tube with a predetermined expanding force.

Another object is to provide structure as set forth above wherein the means for providing an indication of the rolling-in of the tube comprises a U-shaped cantilever spring positioned to be compressed in response to a predetermined expanding force exerted by the tube expander and an indicator secured to the spring for movement on compression of the spring during a tube expanding operation.

Another object is to provide tube expander structure as set forth above and further including means operably associated with said spring for variably preloading the spring.

Another object is to provide tube expander structure as set forth above and further including a cape operably associated with a tube to be expanded and the tube expander for maintaining the cage of the tube expander a predetermined distance from the header the tube is to be connected to, to provide a predetermined flared end on the tube prior to completing the rolling-in of the tube.

Another object is to provide structure as set forth above wherein meshed, shallow rounded teeth are provided, operable between the said one roller and spring so that a predetermined force between the roller and spring, the roller will rotate relative to the spring to provide a rasping noise as an indication of the use of optimum expanding force in rolling-in of a tube.

Another object is to provide structure for and a method of determining the expanding force provided by a tube expander separate from the force required to overcome resistance to forward travel of the expander rollers and the boiling force provided by the expander.

Another object is to provide structure for and a method of determining the expanding force plus the force required to overcome resistance to forward travel of a roller provided by a tube expander separate from the belling force provided thereby.

Another object is to provide an expanding control for self-feeding boiler tube expanders which is simple in construction, economical to manufacture and etficient in use.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

FIGURE 1 is an elevation view of a boiler tube expander including an expanding control constructed in accordance with the invention and illustrating the tube expander in assembly with a header, a boiler tube being expanded and a boiler tube expander cape all of which are shown in section.

FIGURE 2 is a side elevation of a cantilever spring forming a part of the expanding control of the invention.

FIGURE 3 is a top view of the cantilever spring illustrated in FIGURE 2.

FIGURE 4 is an illustration of a properly formed boiler tube flare produced by the tube expander illustrated in FIGURE 1.

FIGURE 5 is an illustration of an improperly formed boiler tube flare.

FIGURE 6 is an enlarged section view through a portion of the cage of the tube expander illustrated in FIG- URE 1 taken substantially on the line 6-6 in FIGURE 1.

FIGURE 7 is a section view of the tube expander illustrated in FIGURE 1 similar to the section view of FIG- URE 6 but taken at substantially ninety degrees with respect thereto in a clockwise direction as illustrated in FIGURE 1.

FIGURE 8 is a section view similar to the section view of FIGURE 7 and illustrating the cantilever spring of the expanding control completely collapsed and the control indicating member thereof in an outer position.

FIGURE 9 is an enlarged section view of a tube expander similar to that illustrated in FIGURE 6 wherein means is provided to permit measuring axial thrust thereon.

FIGURE 10 is a section view of a tube expander similar to FIGURE 9 wherein the feed end of the roller has been shortened and the front end of the roller has been rotatably mounted in the front end of the expander cage rather than abutting the feed end of the expander cage whereby no force tending to resist forward travel of the cage is exerted by the roller.

FIGURE 11 is an elevation view of a modification of the. expanding control illustrated in FIGURE 1.

With particular reference to the figures of the drawings one embodiment of the present invention will now be described in detail.

The boiler tube expander illustrated in FIGURE 1 including the expanding control 12 constructed in accordance with the invention is shown in conjunction with a boiler tube 14 in header 16 and expander cape 13. The expanding control 12, as shown in FIGURE 1, includes the U-shaped cantilever spring 20, the relatively stiff wire 22 and the control indicating member 24.

In operation during the expanding of the boiler tube 14 by the boiler tube expander 10, after the flare 36 has been formed with the aid of cape 18 the control roller 26 provides end thrust on thecantilever spring 20 due to the expanding forces exerted on the tube 14 which will collapse thespring 20 only after a predetermined expanding force is exerted by the tube expander 10. On collapsing of the spring 20 the control indicating member 24 will protrude from the cage 28 of the tube expander 10 to indicate that thetube 14 has been rolled-in with predetermined expanding force. Thereafter, the control roller 26 acts in the same-manner as the other rollers 30.

Self-feeding boiler tube expanders differ in size or shape in order to meet different conditions. However, all known self-feeding tube expanders are similarly constructed and operate in accordance with the same general principles. Before considering the structure and operation of the expanding control '12 in detail, the construction and operation of self-feeding tube expanders including belling or flaring rollers will therefore be reviewed.

Self-feeding boiler tube expanders consist of a central loose, tapered mandrel 32 and a surrounding hollow cylindrical cage 28 having several slots 34 machined therein to receive reverse tapered rollers, such as expanding rollers 30. Slots 34 hold rollers 30 loosely against axial movement while permitting rotation and limited radial movement thereof. The slots 34 are machined at a predetermined feed angle to the longitudinal axis of the cage and mandrel.

The rollers 30 are generally cylindrical with a radially outer surface which is tapered so that the rollers in contact with the mandrel the outer portion of the surface thereof with respect to the mandrel extends parallel to the longitudinal axis of the tapered mandrel. The rollers 30 are provided with an arcuate feed end portion for aiding in feeding the rollers into the tube 14.

Belling rollers 42 are secured in the cage 28 for rotation at an oblique angle to the axis of the mandrel 32. The belling rollers 42 form the flare 36 on the end 38 of the tube 14.

In operation of the usual tube expander 10 the cage 28 is positioned at the open end 38 of the boiler tube 14 and the mandrel '32 is rotated. Rotation of the mandrel 32 produces opposite rotation of the expanding rollers 30.

The rollers 30 are caused to move into the end 38 of the boiler tube 14 due to the feed angle at which the rollers 30 are positioned in the cage 28. Rollers 30 carry cage 28 along with them in their movement into the end 38 of tube 14. The speed of movement of the rollers 30 into the end 38 of tube 14 depends on the speed of rotation of the mandrel 32 and the feed angle which is usually between one and one-half and three degrees.

During movement of the rollers 30 into the end 38 of tube 14, the arcuate feed ends 40 thereof, best shown in FIGURE6, expand or press down the tube material ahead of the rollers '30. The arcuate feed ends 40 of the rollers 30 are necessary to press down the tube material ahead of the rollers without cutting the material of the tube which is undesirable.

During the moving of the cage 28 into the end 38 of tube 14 no substantial pressure is provided outwardly on the rollers 31) due to movement of the mandrel 32 inwardly of the tube '14 relative to the cage 28 since at this time the cage 28 and mandrel are free to move into the tube 14 with the rollers 39. Obviously no belling force is provided by the belling rollers 42 at this time since the belling rollers 42 are not in contact with the tube 14 until the cage 28 has moved into the end of the tube 14 a considerable distance. Any power expended by the tube expander 15 at this time is consumed in moving the cage 28 carrying the rollers 30 and the mandrel 32 into the tube 14.

\Vhen the cage 28 has been moved into the end 38 of tube 14 sufiicicntly to permit the engagement of the belling rollers 42 with the end 38 of the tube 14, the axial force tending to move the cage into the tube 14, which is due to the rotation of the rollers 30 and the feed angle thereof acting against the feed end of the slots 34, that is the end first entering the tube 14, is resisted by the belling force produced by rollers 42 for providing the flare 36 on the end 38 of the tube 14.

The belling or flaring force must be controlled to produce a properly flared boiler tube in accordance with the boiler codes, as illustrated in FIGURE 4. Excessive belling force will produce undesirable flares, such as illustrated in FIGURE 5, where the flare is deeper than desired and the edge 44 of the opening 46 in the header 16 is obje-ctionably rounded.

The cape 18 is a hat-shaped member having an opening .48 extending therethrough which is of sufficient diameter and is shaped to allow the end 5d of the cage 28 including the belling rollers 42 to pass therethrough. Cape 18 engages the radially extending flange S2 at the front end 54 of the cage 28 to flx the axial position of the belling rollers 42 with respect to the header 16 to prevent excessive belling forces and flares such as illustrated in FIGURE 5 from occurring.

When the belling rollers 42 engage the end 38 of the tube 14 to form flare 36 there are opposing forces acting on the cage 28, as indicated before. The belling rollers 42 tend to hold the cage out of the tube 14 and thus provide a force on the cage 28 acting axially outward of the tube end 38 while the usual rollers 30 of the expander 10 provides an inward force on the cage 28 due to their feed angle.

Also, a second downward force on the rollers is produced due to the fact that as the rollers 31) are rotated in frictional engagement with the inner diameter of the end 38 of tube 14 and the expander mandrel 32, the rollers 31) which are prevented from further movement into the tube 14 by the cage 28 tend to feed the mandrel 32 axially into the tube 14. Movement of the mandrel 32 axially into the tube 14 through the cage 28 will produce a radially outward force on the reversely tapered rollers 30 causing them to expand the tube end 38 into engagement with the header 16. The radially outward force on the rollers 30 is commonly known as the expanding force and is proportional to the axial force acting on the rollers 30 to produce the radial movement of the rollers.

Thus during the normal operation of a boiler tube expander 10 three axial forces are produced in rollers 39.. First, a force tending to overcome the resistance to movement of rollers 30 into the boiler tube is produced. Subsequently belling and expanding forces acting on rollers 30 are produced to provide a flare 36 on the end 38 of the boiler tube 14 and to expand the end 38 of the boiler tube 14 into the opening 46 in the header 16. Each of these forces acts between the feed ends of the slots 34 in cage 28 and the feed or inner ends of the rollers 30.

While a cape 18 can effectively prevent overflaring of a boiler tube joint and thus renders the exact control of the belling :force unnecessary, to produce a properly rolled-in boiler tube joint it is desirable to determine the force tending to overcome the resistance to movement of the rollers into the tube 14, the belling and the expanding force indicated above and acting on the usual expander rollers 30 during rollingin of a boiler tube joint.

The structures and methods used in the past for determining the expanding force exerted by the rollers '30 in a rolling-in process have been unsatisfactory, requiring for example the measurement of the axial elongation of the tube 14 due to the working of the end 38 thereof in the rolling-in process with separate gages, switches and the like.

In accordance with the invention a method of and means for separately determining the force resisting movement of the rollers 30 into the tube end 38, the expanding force and belling force necessary to produce a properly rolled-in boiler tube is provided. Thus, as shown in FIGURE 9, compressible, thin sheets of material, such as blotting paper or lead 56, are positioned beneath the end 40 of a roller 30 in a tube expander 10. After rollingin of a tube 14, the compression of the blotting paper or lead sheets 56 may be measured as an indication of the total axial force on one roller required to roll-in tube 14.

To isolate the force required to resist movement of the rollers 30 into the tube and the expanding force from the belling force, it is only necessary to repeat the above process with the belling rollers 42 removed from the expander 10.

To isolate the force required to resist movement of the rollers 30 into the tube from the expanding force the end portion 40 of one of the rollers 30 of a tube expander is removed as shown in FIGURE 10 so that the force required to resist movement of the rollers 30 into the tube formerly exerted on the end of the one roller 30 is taken up by the other rollers 30 of the tube expander. The one roller 30 is rotatably mounted in a bearing 62 secure-d in the cage 28 and the axial force produced in the one roller 30 by the expanding force is measured by placing the blotting paper or lead sheets 56 between a mounting washer 64 and the front end of the mounting bushing 62 for the one roller 30. The resulting force indication is the expanding force which need only be subtracted from the above determined combined expanding force and force required to resist movement of the one roller 30 into the tube 14.

Since the forces operable in a tube expander 10 may be separated as indicated above, it is possible to determine the optimum force necessary to expand particular tubes into particular headers with accuracy. Further, since most tube expanders are ordered for particular tube sizes and installation, it is considered practical to produce tube expanders which are calibrated to provide an indication of a predetermined expanding force variable within a relaatively narrow range.

In the rolling-in of a boiler tube in accordance with the invention both cage 28 and mandrel 32 are inserted into the loose end 33 of tube 14 as far as they will go in order to facilitate an early forming of the flare 36. Any slack between the rollers 38 and the inner surface of tube 14 is thus taken up. Rotation of mandrel 32 and consequent forward feed of cage 28 will then expand the tube end 38 slowly until the tube hole clearance is taken up and full metal-to-metal contact is attained between tube 14 and the tube hole.

Further rolling will then compress the tube 14 and tube hole metal and thus generate enough friction and force to start the flare 36. In consequence the whole expander 10 will move forward into the joint until the flare 36 is formed and the cape 18 contacts the header 15.

At the same time the continuous forward travel of the mandrel keeps on expanding the tube joint until completion of the rolling-in of tube 14 is indicated by the expanding control 12.

Most of the rolling-in force will be belling force initially due to the starting position of the cage 23 and mandrel 32. Consequently the belling will be completed before the expanding force becomes excessive. The belling force need not be accurately controlled during this portion of a rolling-in operation since the cape 18 is used to limit forward travel of belling rollers 26.

After the flare 36 has been formed in the boiler tube 14 it is desired to provide an indication to an operator at the time that the expanding force has reached the optimum value. To provide an indication of complete expanding of a boiler tube, the end of the control roller 26 in the tube expander 10 is removed as illustrated in FIG- URES 7 and 8 and a cantilever spring 20 is positioned beneath the end of the control roller 26. The cantilever s ring 26 is calibrated to permit axial movement of the roller 26 only after a force representative of the optimum expanding force is produced axially of the roller 26.

A pressure plate 70 is provided between the control roller 26 and the cantilever spring 20, as shown best in FIGURES 7 and 8. In accordance with the above discussion the axial force provided on the control roller 26 will be only that due to the expanding force exerted by the tube expander 10. Further, the force on the control roller 26 will be representative of the total expanding force exerted by all of the rollers since in the case of each of the forces it has been found that the usual rollers 30 each do a proportionate share of Work and if a particular force, such as the belling force, is not resisted by one of the rollers, the other rollers divide the force usually taken up by the roller not operating to resist the particular force.

The cantilever spring 20, as shown best in FIGURES 2 and 3, is a generally U-shaped member having a thinner resilient cantilevered portion 72 on one leg 74 thereof, as illustrated in FIGURE 7. The other leg 76 of the U-shaped member is terminated in an upwardly extending portion 78 engaging the cantilevered portion 72 of the one leg of spring 20. The extending portion 73 of the spring 20 is of sufiicient length so that when the legs 74 and 76 of the spring 20 are collapsed into surface-to surface engagement the extension 78 causes the canti- -ievered portion 72 of the spring 20 to bend upwardly, as shown in FIGURE 8, within the elastic limit of the cantilevered portion 72.

An indicator member 24 is reciprocally mounted within the axial opening 80 in the cage 28 on the relatively rigid resilient wire 82. The wire 82 is connected to the cantilevered portion 72 of the spring 20 by means of the slot 84 in the spring 20.

Thus in operation, when the expanding force exerted by the tube expander 10 is of sufiicient magnitude to collapse the spring 20 and move the legs74 and 76 of the spring 20 together, the cantilevered end 72 of the spring 26 in contact with the portion 78 thereof moves upward as illustrated in FIGURE 8 to move the indicating member 24 upward and out of the front end 54 of the cage 28 to provide an indication that the tube 14 has been expanded by a predetermined force at which the spring 29 is calibrated.

On movement of the indicating member 24 out of the cage 23, the tube 14 should be expanded to an optimum degree and any additional operation of the tube expander 16 should be held to a minimum required to finish the tube joint, such as finishing the expanded surfaces of the tube end 38 and completing the flare 36. Control of the forming of the flare 36 as previously indicated is pri marily by the use of a cape 18.

In the modified tube expander structure illustrated in FIGURE 11 wherein similar structure has been designated by reference numerals similar to those used in FIGURE 1, the indicating member 24 is connected to operate a switch 86 connected in the energizing circuit diagrammatically illustrated by conductors 96 for the tube expander 10 to break the energizing circuit of the modified tube expander to cease operation thereof at optimum tube expanding pressure.

Additionally the modified tube expander 10 is constructed to provide an audible as well as a visual indication of optimum tube expanding force, by the provision 7 of shallow rounded teeth 88 on the feed end of the roller 26 and on theengaging surface of spring 20, as illustrated in FIGURE 11, which slip when a predetermined force is provided therebetween to provide a rasping sound. The audible'indication alone may be provided as will be readily understood and the rounded teeth may be provided on the pressure plate 70 where one is provided rather than on spring 29 as indicated in FIGURE 8.

While it has been indicated that the spring 29 is precalibrated for a predetermined job to provide optimum rolling-in of a tube having a predetermined diameter in an opening of predetermined size, means are provided for varying the action of the spring within certain limits. Thus the screw 92, illustrated in FIGURES 7 and 8, is provided to vary the action of the spring on movement of the screw 92 axially in the passage Wt to provide a greater or lesser preload on the spring 26.

If it is desired to use weaker springs 20 in conjunction with roller 26 the expanding force provided by roller 26 can be reduced by cutting a groove 98 in the roller surface as shown in FIGURE 11. The groove 98 should be circular or spiral to maintain the roller balance While one embodiment of the present invention and modifications thereof have been considered in detail, it will be understood that other embodiments and modifications are contemplated. It is therefore the intention to include all embodiments and modifications of the invention as are defined by the appended claims within the scope of the invention.

What I claim as my invention is:

1. A tube expander comprising a hollow outer cylindrical cage having longitudinally extending slots therethrough angularly spaced apart therearound, a tapered mandrel extending axially through the cage, a plurality of reversely tapered expanding rollers having feed and front ends positioned in the slots in-the cage in engagement with the tapered mandrel for rotation and radial movement inresponse to rotation and axial movement of the mandrel through the cage, and means operably associated with at least one of the rollers for providing an indication of a predetermined expanding force exerted by the rollers including a collapsible spring operable between the feed end of the one roller and the cage, an indicating member reciprocably mounted to extend through the front end of the cage and means connecting the indicating member to the collapsible spring for movement outwardly of the front end of the cage on collapsing of said spring.

2. Structure as set forth in claim 1, wherein said spring is U-shaped, one leg of the spring is terminated in a resilient extension the end of which is connected to the indicating member and which extends substantially beyond the end of the other leg and the other leg is terminated in a portion extending at right angles thereto toward the one leg, which portion is of greater longitudinal extent than the depth of the one leg whereby on collapsing of the spring to move the legs together the portion of the other leg contacts the extension of the one leg and flexes the extension.

3. Structure as set forth in claim 1, and further including means for variably prestressing the spring.

4. Structure as set forth in claim 3, wherein the means for variably prestressing the spring comprises a set screw extending axially within said cage and engaged with the spring for prestressing said spring on axial movement thereof.

5. Structure as set forth in claim 1, wherein a pressure plate is provided between the end of the one roller and the spring, and the end of the one roller and the pressure plate include meshed, shallow rounded teeth thereon for providing a rasping sound on collapsing of said spring due to the expanding force exerted by the rollers exceedinn aid predetermined expanding force.

6. Structure as set forth in claim 1, and further including a switch in the energizing circuit for the tube expander engaged with the indicating member for opening the energizing circuit for the tube expander-on collapsing of the spring.

7. A calibrated cantilevered spring comprising a generally U-shaped spring member having a resilient relatively rigid extension on one leg thereof extending from the end thereof and in the same direction thereas, the other leg of the U-shaped member terminating in a portion extending at right angles thereto which portion is greater in length than the thickness of said other leg and extends toward the extension on the one leg of the U- shaped member transversely thereof for engaging and flexing the extension with the spring collapsed to place the legs thereof in side by side relation.

8. Structure for determining the expanding force and force resisting axial movement of the rollers into a tube applied to the rollers of a tube expander including expanding rollers having a front end and a feed end and a cage comprising, means for securing a roller of the tube expander for rotation to the front end of the cage with the feed end of the one roller out of engagement with the cage and compressible means extending transversely between the one roller and the front end of the cage for compression thereby axially of the tube.

9. Structure as set forth in claim 8, wherein the rollers of the tube expander include arcuate feed ends and the arcuate feed end of the one roller has been completely removed whereby only the expanding force is exerted by the one roller on the compressible means.

10. A tube expander comprising a hollow outer cylindrical cage having longitudinally extending slots therethrough angularly spaced apart therearound, a tapered mandrel extending axially through the cage, a plurality of reversely tapered expanding rollers having feed and front ends positioned in the slots in the cage in engagement with the tapered mandrel for rotation and radial movement in response to rotation and axial movement of the mandrel through the cage, and means operably associated with at least one of the rollers for providing an indication of a predetermined expanding force exerted by the rollers including a collapsible spring positioned between the feed end of the one roller and the cage and meshed, shallow rounded teeth on the spring and the feed end of the roller for providing a rasping sound on collapsing of said spring due to the expanding force exerted by the rollers exceeding said predetermined expanding force.

11. In a boiler tube expander including a cage and expanding rollers having a feed end, structure for providing an indication of a predetermined expanding force applied to a tube by the tube expander including a U-shaped spring positioned between the feed end of one of the expanding rollers and the cage operable to collapse on a predetermined expanding force being applied to the one roller, an indicating member mounted for reciprocable movement in the cage and means connecting said indicating member and spring for moving the indicating mem ber outwardly of the cage on collapsing of the spring.

12. In a boiler tube expander including a cage and expanding rollers having a feed end, structure for providing an indication of a predetermined expanding force applied to a tube by the tube expander including collapsible means positioned between the feed end of one of the rollers of the tube expander and the cage thereof and meshed, shallow rounded teeth on the collapsible means and the feed end of the one roller for producing a rasping sound on collapsing the collapsible means.

13. Apparatus for expanding a boiler tube in a header or the like comprising a tube expander including a hollow outer cylindrical cage having a radially outwardly extending annular flange around one end thereof and longitudinally extending slots therethrough angularly spaced apart therearound, a tapered mandrel extending axially through the cage, a plurality of reversely tapered expanding rollers having feed and front ends positioned in the slots in the cage in engagement with the tapered mandrel for rotation and radial movement in response to rotation and axial movement of the mandrel through the cage, means operably associated with at least one of the rollers for providing an indication of a predetermined expanding force exerted by the rollers including a collapsible spring operable between the feed end of the one roller and the cage, an indicating member reciprocably mounted to extend through the front end of the cage and means connecting the indicating member to the collapsible spring for movement outwardly of the front end of the cage on collapsing of said spring, and a plurality of belling rollers secured to said cage and extending obliquely therefrom in angularly spaced apart positions therearound adjacent said one end thereof and a cape comprising a cup-shaped member having an opening therethrough receiving said cage with the periphery of said opening in engagement with the annular flange on said cage the open end of the cape including an annular surface for abutting a header in which a tube is being expanded on completion of flaring of the tube end.

14. Apparatus for expanding a boiler tube in a header or the like comprising a tube expander including a hollow outer cylindrical cage having a radially outwardly extending annular flange around one end thereof and longitudinally extending slots therethrough angularly spaced apart therearound, a tapered mandrel extending axially through the cage, a plurality of reversely tapered expanding rollers having feed and front ends positioned in the slots in the cage in engagement with the tapered mandrel for rotation and radial movement in response to rotation and axial movement of the mandrel through the cage means operably associated with at least one of the rollers for providing an indication of a predetermined expanding force exerted by the rollers including collapsible means positioned between the feed end of one of the rollers of the tube expander and the cage thereof and meshed, shallow rounded teeth on the collapsible means and the feed end of the one roller for producing a rasping sound on collapsing of the collapsible means, and a plurality of belling rollers secured to said cage and extending obliquely therefrom in angularly spaced apart positions therearound adjacent said one end thereof and a cape comprising a cup-shaped member having an opening therethrough receiving said cage with the periphery of said opening in engagement with the annular flange on said cage, the open end of the cape including an annular surface for abutting a header in which a tube is being expanded on completion of flaring of the tube end.

References Cited UNITED STATES PATENTS 379,502 3/1888 Brinkerhoff 2671 996,315 6/1911 Clifford 266-1 1,307,775 6/1919 Hacker 73-94 1,412,277 4/1922 Dixon 721 19 1,793,624 2/1931 Lang 72-122 2,526,025 10/1950 Hoeppe 721 19 2,718,964 9/1955 Kilgore 2671 3,105,887 10/1963 Korsgren, et al 2671 RICHARD J. HERBST, Primary Examiner. 

1. A TUBE EXPANDER COMPRISING A HOLLOW OUTER CYLINDRICAL CASE HAVING LONGITUDINALLY EXTENDING SLOTS THERETHROUGH ANGULARLY SPACED APART THEREAROUND, A TAPERED MANDREL EXTENDING AXIALLY THROUGH THE CAGE, A PLURALITY OF REVERSELY TAPERED EXPANDING ROLLERS HAVING FEED AND FRONT ENDS POSITIONED IN THE SLOTS IN THE CAGE IN ENGAGEMENT WITH THE TAPERED MANDREL FOR ROTATION AND RADIAL MOVEMENT IN RESPONSE TO ROTATION AND AXIAL MOVEMENT OF THE MANDREL THROUGH THE CAGE, AND MEANS OPERABLY ASSOCIATED WITH AT LEAST ONE OF THE ROLLERS FOR PROVIDING AN INDICATION OF A PREDETERMINED EXPANDING FORCE EXERTED BY THE ROLLERS INCLUDING A COLLAPSIBLE SPRING OPERABLE BETWEEN THE FEED END OF THE ONE ROLLER AND THE CAGE, AN INDICATING MEMBER RECIPROCABLY MOUNTED TO EXTEND THROUGH THE FRONT END OF THE CAGE AND MEANS CONNECTING THE INDICATING MEMBER TO THE COLLAPSIBLE SPRING FOR MOVEMENT OUTWARDLY OF THE FRONT END OF THE CAGE ON COLLAPSING OF SAID SPRING. 